19778653521 has 32 divisors (see below), whose sum is σ = 32150355840. Its totient is φ = 11917742400.

The previous prime is 19778653501. The next prime is 19778653529. The reversal of 19778653521 is 12535687791.

19778653521 is a `hidden beast` number, since 1 + 9 + 7 + 7 + 86 + 535 + 21 = 666.

It is not a de Polignac number, because 19778653521 - 2¹³ = 19778645329 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19778653529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 141090 + ... + 243851.

It is an arithmetic number, because the mean of its divisors is an integer number (1004698620).

Almost surely, 2^19778653521 is an apocalyptic number.

19778653521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19778653521 is a deficient number, since it is larger than the sum of its proper divisors (12371702319).

19778653521 is a wasteful number, since it uses less digits than its factorization.

19778653521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385134 (or 385128 counting only the distinct ones).

The product of its digits is 3175200, while the sum is 54.

The spelling of 19778653521 in words is "nineteen billion, seven hundred seventy-eight million, six hundred fifty-three thousand, five hundred twenty-one".